THE ORIGIN OF THE EARTH! 
By THornton Pace 
Yerkes Observatory 
[With 11 plates] 
With all the spectacular success of recent scientific research, it is 
perhaps refreshing to examine a field so characterized by failure as this 
one. Although many speculations have been described as ‘‘theories,”’ 
there exists today no real theory of the origin of the earth in the sense 
of a complete logical structure linking together the vast quantity of 
pertinent observations collected during the last century. 
The most obvious approach to the problem is to study the visible 
surface of the earth for clues to its origin. This has been done in 
detail by geologists, geodesists, geophysicists, and geochemists, but it 
is perhaps not surprising that what they find has more to do with the 
earth than with its origin. It has been the astronomer, studying the 
relation of the earth to its surroundings, and the physicist, studying 
the behavior of matter, who have made the greatest progress in the 
study of the earth’s origin. 
Early speculation on the subject was simple and direct because there 
were fewer observations to explain. The assumption of a divine crea- 
tion of things as they are was generally accepted until the end of the 
sixteenth century. Then the revolution in scientific thinking, started 
by Galileo, turned men from assumptions of a catastrophic origin to a 
belief in natural development, understandable in terms of what can 
be seen and measured today. As the astronomical picture became 
clearer, it appeared that the earth is a relatively small, nearly spherical 
body moving around the sun together with the other planets, all under 
the influence of the sun’s gravitational attraction. It was soon 
recognized as scarcely due to chance that all the known planets and 
their satellites are moving and rotating in the same direction, their 
orbits nearly circular, and in nearly the same plane. Therefore, in 
1755, the great German philosopher-scientist, Immanuel Kant, specu- 
lated that the planets and the sun were formed from a single large 
rotating gaseous cloud, or nebula, which had condensed into smaller 
rotating parts, these further condensing into rotating planets with 
1 Reprinted by permission from Physics Today, vol I, No. 6, October 1948. 
161 
